For typical gas distribution systems, the fluid pressure may vary according to the demands placed on the system, the climate, the source of supply, and/or other factors. However, most end-user facilities equipped with gas appliances such as furnaces, ovens, etc., require the gas to be delivered in accordance with a predetermined pressure, and at or below a maximum capacity of a piece of equipment. Fluid regulators are used to regulate the output pressure of a fluid, such as a liquid or a gas, to meet a desired pressure in a supply line. Therefore, fluid regulators are installed in these distribution systems in order to ensure that the delivered fluid meets the pressure and/or capacity requirements of the end-user facilities.
FIGS. 1 and 2 illustrate one example known fluid regulator 10. The fluid regulator 10 includes a regulator body 12 having an inlet 14 coupled to an outlet 16 by a fluid passageway 18, a flow control member 20 disposed in the regulator body 12 and arranged to shift toward and away from a valve seat 22 so as to control the flow of fluid through the fluid passageway 18. An O-ring 19 is assembled on the inlet fitting. An actuator 24 is coupled to the regulator body 12, and includes a pressure sensing element, such as a diaphragm 26, that forms a wall of a pressure chamber 27, which is in fluid communication with the outlet 16 so as to sense fluid pressure at the outlet 16. An actuator stem 28 is coupled to the diaphragm 26 and arranged to move up and/or down with the diaphragm 26 in response to changes in fluid pressure at the outlet 16. A lever 30 is operatively coupled to each of the flow control member 20 and the actuator 24 to convert the movement of the diaphragm 26 into a corresponding movement of the flow control member 20 to maintain the outlet pressure at a preselected level. In particular, the lever 30 operatively couples the actuator stem 28 with the flow control member 20 and pivots to transfer the vertical movement of the actuator stem 28 into the horizontal movement of the flow control member 20. The lever 30 has an arm extending between a first end, e.g., a front end 34, and a second end, e.g., a back end 40, and the lever 30 is pivotably coupled to the regulator body 12 by a pin 32. The front end 34 is coupled to the flow control member 20 by a second pin 36 that is slidably disposed within a notch 38 at the front end 34 of the lever 30. The back end 40 of the lever 30 is coupled to the actuator stem 28 by a hooked portion 42 that is downwardly angled at the second end 40 of the lever 30 and hooked over a saddle 44 at a lower end of the actuator stem 28. A spring 46 presses against a top side of the diaphragm 26 opposite from the pressure chamber 27.
As best seen in FIG. 2, the lever 30 generally has the form of a flat plate having two opposite parallel sides. An outer periphery of the lever 30 is defined by top and bottom edges, and the pin 32 extends transversely through the two sides of the lever 30. The pin 32 is pivotably carried within a slot 47 of a lever receiver 48 that is coupled to the regular body 12. The lever receiver 48 allows the lever 30 and/or the pin 32 to rotate about an axis A of the pin 32 within the plane of the lever 30 perpendicular to the axis A.
Again referring to FIG. 1, in operation, as fluid flows through the regulator body 12 from the inlet 14, past the valve seat 22 (which is shown here in a closed position), and toward the outlet 16, the fluid pressure near the outlet 16 also presses upwardly against the diaphragm 26. The fluid pressure near the outlet 16 and the force the spring 46 together move the diaphragm 26 up and/or down in response to fluctuating fluid pressures at the outlet 16. The movement of the diaphragm 26 correspondingly moves the actuator stem 28 and the second end 40 of the lever 30 up and/or down. As the second end 40 of the lever 30 moves up or down, the lever 30 pivots about the pin 32, which causes the first end 34 to move horizontally back and forth, and thereby converts the vertical movement of the actuator stem 28 into the horizontal movement of the flow control member 20.
The positioning of the lever 30 is typically carefully calibrated so that movements of the diaphragm 26 cause the flow control member 20 to move toward or away from the valve seat 22 a predetermined distance. In a highly pressurized environment, however, rapid changes in the fluid pressure at the inlet 14 may cause the flow control member 20 and the lever 30 to oscillate rapidly, which may lead to an undesirable oscillation typically called “valve flutter.” Such valve flutter can lead to undesirable effects, such as excessive wear of the flow control member 20 and/or the various connections between the flow control member 20, the lever 30, and the actuator stem 28, all of which may lead to a loss of accuracy and/or responsiveness of the fluid regulator 10. Accordingly, it would be desirable to provide a fluid regulator that can reduce or eliminate valve flutter.